Damselfish comprise the family Pomacentridae except those of the genera Amphiprion and Premnas, which are the anemonefishes. They can grow up to 14 inches (36 cm) long. While most are marine, a few species inhabit the lower stretches of rivers in freshwater. Damselfish usually have bright colors.
Many species live in tropical coral reefs, and many of those are kept as marine aquarium pets, although not the white-spotted damselfish. Diet includes small crustaceans, plankton, and algae. However, many also live in temperate climates, such as the species which inhabits the coast of southern California and the Pacific Mexican coast, the garibaldi.
Aquarists often use damselfish to biologically stabilize a new aquarium. The fish is introduced when the aquarium is first populated, and helps provide beneficial bacteria. This practice is viewed negatively by some aquarists because of what they see as foul conditions and the fact other, slower, stabilization methods exist.
At this time, garibaldi and damselfish are the only fish known to engage in farming or cultivating.
There is geographic variation in the damselfish/red-alga cultivation mutualism in the Indo-West Pacific. Damselfish are also known to be aggressive, especially the twospot domino damse